Single turbo timing corrections normal or not?

bostons335i

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Oct 17, 2022
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Hey guys wondering if I could get some help with my single turbo n54. I’ve got it on e75 with a JB4 bef for e and was trying out 23psi and 26psi . I seem to be getting some trimming corrections on the logs ill attached. I was just wondering if this is “normal” or not? Some posts I see on the forums have absolutely no timing corrections others do , so I’m confused where I stand . Thank you in advanced ! Please let me know if the logs get on correctly this is my first time posting!
 

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  • P30_M4_R3_230512_2000 may12.csv
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carabuser

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The log is pretty much meaningless as the JB4 doesn't seem to log timing corrections at all rather just logs the individual cylinder timing and doesn't show negative numbers so you really have no idea what sort of corrections you are getting.

In general though timing corrections are somewhat normal. I'm never concerned by an infrequent -3 or less correction across random cylinders during a pull. Any correction larger than -5 is a concern as this indicates more noise in the cylinder.

The issue with single turbo cars is that they often come along with non OE engine components like upgraded rods, pistons and blocks and also HPFP overdrive kits which change the noise characteristics of the engine that the knock detection routines are set up for. There is no realistic way to re-tune these parameters without a lab so the typical approach is to just reduce the sensitivity of these tables to match the new baseline noise levels. This just leaves a larger window for real knock to go unnoticed and uncorrected.

The other issue is that lazy tuners often keep reported load artificially low. Most of the knock tables are based around engine airflow so the more you mis-report load, the greater the gap will be between the knock model that BMW created for the engine and the reality. You're seeing a reported load of 172 at 23psi which is going to throw everything off.
 
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bostons335i

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Oct 17, 2022
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Hey thab
The log is pretty much meaningless as the JB4 doesn't seem to log timing corrections at all rather just logs the individual cylinder timing and doesn't show negative numbers so you really have no idea what sort of corrections you are getting.

In general though timing corrections are somewhat normal. I'm never concerned by an infrequent -3 or less correction across random cylinders during a pull. Any correction larger than -5 is a concern as this indicates more noise in the cylinder.

The issue with single turbo cars is that they often come along with non OE engine components like upgraded rods, pistons and blocks and also HPFP overdrive kits which change the noise characteristics of the engine that the knock detection routines are set up for. There is no realistic way to re-tune these parameters without a lab so the typical approach is to just reduce the sensitivity of these tables to match the new baseline noise levels. This just leaves a larger window for real knock to go unnoticed and uncorrected.

The other issue is that lazy tuners often keep reported load artificially low. Most of the knock tables are based around engine airflow so the more you mis-report load, the greater the gap will be between the knock model that BMW created for the engine and the reality. You're seeing a reported load of 172 at 23psi which is going to throw everything


Hey man thank you so much for the reply ! I just have a couple questions .

Does MHD log actual timing corrections into the negative ? I might do a log with it instead to see what the timing is actually looking like .

On this load parameter what actually is that? They give such a vague definition on JB4 tech I don’t understand what it is . But I’m now on 26 psi and the load went up to 180.

Also not sure if this makes any difference but my cars motor is actually stock , I’ve only done external mods , I do have port injection and all the supporting mods would those also contribute to the noise you mentioned ? (Very much novice with these tuning definitions)

Lastly are the JB4 BEFs just not safe? It’s starting to seem like these are just blanketed tunes and the cars not tuning right ? Thank you !
 

carabuser

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MHD will show the actual correction parameters. The JB4 may also be able to do it but I've never looked at them in that much detail.

The load parameter is essentially the amount of cylinder fill. The best way to think of it is that 100% load is the maximum that a non-turbo engine (some can actually operate higher but we'll keep it simple) can operate at. Anything higher than 100% is the result of forced induction, so 200% load would be twice the amount of air/fuel in the cylinder.

The relationship between boost in the manifold and load is non-linear because having twice the pressure in the manifold doesn't equate to twice as much air in the cylinder due to restrictions through the intake port. To get 200% load on the stock intake/head you make need 250% atmospheric pressure in the manifold, the ECU calculates this relationship through the "volumetric efficiency" model.

Due to software limitations in the DME, it can only see 22psi of actual boost so once you get up past 260~ load in a tune the DME will cap out on its boost target and you need to start scaling so there's no perfect solution. But you'd be a lot closer to reality reporting 250 load than 160.

I'm probably the last person you want to ask for unbiased advice on a JB4, I'd personally rather drive a stock vehicle than go anywhere near one of those. But my advice for someone that's spent a good amount of money on hardware to go single is to also invest a little in a proper tune. These days you can control a single turbo purely from the DME with no need for an external boost controller. You'd still need something to control PI but I think the Reflex is much better at than than the JB4.
Wedge does a pretty good job with tuning single turbo vehicles, he's probably the only person I could recommend on the N54 platform if you wanted to move away from the JB4.
 

bostons335i

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Oct 17, 2022
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MHD will show the actual correction parameters. The JB4 may also be able to do it but I've never looked at them in that much detail.

The load parameter is essentially the amount of cylinder fill. The best way to think of it is that 100% load is the maximum that a non-turbo engine (some can actually operate higher but we'll keep it simple) can operate at. Anything higher than 100% is the result of forced induction, so 200% load would be twice the amount of air/fuel in the cylinder.

The relationship between boost in the manifold and load is non-linear because having twice the pressure in the manifold doesn't equate to twice as much air in the cylinder due to restrictions through the intake port. To get 200% load on the stock intake/head you make need 250% atmospheric pressure in the manifold, the ECU calculates this relationship through the "volumetric efficiency" model.

Due to software limitations in the DME, it can only see 22psi of actual boost so once you get up past 260~ load in a tune the DME will cap out on its boost target and you need to start scaling so there's no perfect solution. But you'd be a lot closer to reality reporting 250 load than 160.

I'm probably the last person you want to ask for unbiased advice on a JB4, I'd personally rather drive a stock vehicle than go anywhere near one of those. But my advice for someone that's spent a good amount of money on hardware to go single is to also invest a little in a proper tune. These days you can control a single turbo purely from the DME with no need for an external boost controller. You'd still need something to control PI but I think the Reflex is much better at than than the JB4.
Wedge does a pretty good job with tuning single turbo vehicles, he's probably the only person I could recommend on the N54 platform if you wanted to move away from the JB4.
Hey man thank you so much for the much needed information , I’m still super new to getting really into the tuning definitions so I seriously appreciate it as it furthers my understanding of the n54 and tuning in general.

I have also been sort told about the jb4 starting to become obsolete and. I think if the prices for reflex and add ons come down I’ll eventually change but for right now I’ll have to stick with the jb4 .

I did however forget to mention 1 other thing. I have been getting intermittent fuel mixture codes 29e0 and 29e1 . I’ve been heavily investing time to research about this and have sorta suspected a possible issue with the injectors (possibly 1 and 4 which are pulling timing) . I’m going to pull the plugs first to see if they are leaking . All index 12s but I just read a post with the same issues (rough cold start) and same codes and they tracked it down to the injectors so I’ll report back. If this changes anything let me know what else’s I should check ! Thanks again.
 
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Torgus

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With how the reflex seems to be selling I kind of doubt they will drop the price but I hope I am wrong.
 

ShadyOrb

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Hey man thank you so much for the much needed information , I’m still super new to getting really into the tuning definitions so I seriously appreciate it as it furthers my understanding of the n54 and tuning in general.

I have also been sort told about the jb4 starting to become obsolete and. I think if the prices for reflex and add ons come down I’ll eventually change but for right now I’ll have to stick with the jb4 .

I did however forget to mention 1 other thing. I have been getting intermittent fuel mixture codes 29e0 and 29e1 . I’ve been heavily investing time to research about this and have sorta suspected a possible issue with the injectors (possibly 1 and 4 which are pulling timing) . I’m going to pull the plugs first to see if they are leaking . All index 12s but I just read a post with the same issues (rough cold start) and same codes and they tracked it down to the injectors so I’ll report back. If this changes anything let me know what else’s I should check ! Thanks again.
I have this exact same issue. JB4 as well and same codes popping up. Please report back if you find a fix.
I'm about to get my car out for the summer and will have to fix this too.